/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.aop.support;

import java.io.Serializable;
import java.lang.reflect.Method;

import org.springframework.aop.ClassFilter;
import org.springframework.aop.MethodMatcher;
import org.springframework.aop.Pointcut;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;

/**
 * Pointcut and method matcher for use in simple <b>cflow</b>-style pointcut.
 * Note that evaluating such pointcuts is 10-15 times slower than evaluating
 * normal pointcuts, but they are useful in some cases.
 *
 * @author Rod Johnson
 * @author Rob Harrop
 * @author Juergen Hoeller
 */
@SuppressWarnings("serial")
public class ControlFlowPointcut implements Pointcut, ClassFilter, MethodMatcher, Serializable {

    private Class<?> clazz;

    @Nullable
    private String methodName;

    private volatile int evaluations;


    /**
     * Construct a new pointcut that matches all control flows below that class.
     *
     * @param clazz the clazz
     */
    public ControlFlowPointcut(Class<?> clazz) {
        this(clazz, null);
    }

    /**
     * Construct a new pointcut that matches all calls below the given method
     * in the given class. If no method name is given, matches all control flows
     * below the given class.
     *
     * @param clazz the clazz
     * @param methodName the name of the method (may be {@code null})
     */
    public ControlFlowPointcut(Class<?> clazz, @Nullable String methodName) {
        Assert.notNull(clazz, "Class must not be null");
        this.clazz = clazz;
        this.methodName = methodName;
    }


    /**
     * Subclasses can override this for greater filtering (and performance).
     */
    @Override
    public boolean matches(Class<?> clazz) {
        return true;
    }

    /**
     * Subclasses can override this if it's possible to filter out
     * some candidate classes.
     */
    @Override
    public boolean matches(Method method, @Nullable Class<?> targetClass) {
        return true;
    }

    @Override
    public boolean isRuntime() {
        return true;
    }

    @Override
    public boolean matches(Method method, @Nullable Class<?> targetClass, Object... args) {
        this.evaluations++;

        for (StackTraceElement element : new Throwable().getStackTrace()) {
            if (element.getClassName().equals(this.clazz.getName()) &&
                    (this.methodName == null || element.getMethodName().equals(this.methodName))) {
                return true;
            }
        }
        return false;
    }

    /**
     * It's useful to know how many times we've fired, for optimization.
     */
    public int getEvaluations() {
        return this.evaluations;
    }


    @Override
    public ClassFilter getClassFilter() {
        return this;
    }

    @Override
    public MethodMatcher getMethodMatcher() {
        return this;
    }


    @Override
    public boolean equals(Object other) {
        if (this == other) {
            return true;
        }
        if (!(other instanceof ControlFlowPointcut)) {
            return false;
        }
        ControlFlowPointcut that = (ControlFlowPointcut) other;
        return (this.clazz.equals(that.clazz)) && ObjectUtils.nullSafeEquals(that.methodName, this.methodName);
    }

    @Override
    public int hashCode() {
        int code = this.clazz.hashCode();
        if (this.methodName != null) {
            code = 37 * code + this.methodName.hashCode();
        }
        return code;
    }

}
